Pretty sure the library of Congress archives certain sites but there are literally thousands of search engines, marketing companies, researchers, government organisations worldwide all indexing Reddit for their own individual purposes. We can access the earliest forums on the web, some 30+ years ago so it's highly likely every comment you made will be available for you to see. I can see posts I made on long inactive forums regarding topics I've long since moved on from (10 years old) but it's cool to be able to identify certain points that would come to have had a major impact on the shaping of my life, yet at the time seeming no more than a flippant remark or casual conversation